Abstract
5β-Cholestane-3α,7α,12α,26-tetrol:NAD oxidoreductase in a soluble fraction of rat liver was studied. 1. 1. Rat liver 5β-cholestane-3α,7α,12α,26-tetrol:NAD oxidoreductase was purified by ammonium sulfate fractionation, gel filtration, hydroxylapatite column chromatography and ion-exchange column chromatography. The overall purification attained was about 70-fold. 2. 2. 5β-Cholestane-3α,7α,12α,26-tetrol:NAD oxidoreductase was always accompanied by liver alcohol:NAD oxidoreductase (EC 1.1.1.1) activity, and the ratio of these two enzyme activities was constant throughout the purification procedures. 3. 3. Both 5β-cholestane-3α,7α,12α,26-tetrol:NAD oxidoreductase and liver alcohol:NAD oxidoreductase behaved similarly to thermal inactivation and also to inactivation caused by p- chloromercuribenzoate (PCMB). 4. 4. The K i value for pyrazole of 5β-cholestane-3α,7α,12α,26-tetrol:NAD oxidoreductase was found to be about 80 times that of liver alcohol:NAD oxidoreductase. 5. 5. The possibility was discussed that both 5β-cholestane-3α,7α,12α,26-tetrol:NAD oxidoreductase and liver alcohol:NAD oxidoreductase activities may be due to a single enzyme protein.
Published Version
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